A multicenter evaluation was undertaken to evaluate the performance of a new three-color peptide nucleic acid fluorescence in situ hybridization assay that identifies isolates directly from blood cultures positive for Gram-negative bacilli (GNB). The assay correctly identified 100% (186/186) of the Escherichia coli isolates, 99.1% (109/110) of the Klebsiella pneumoniae isolates, and 95.8% (46/48) of the Pseudomonas aeruginosa isolates in this study. Negative assay results were correctly obtained for 162 of 165 other GNB (specificity, 98.2%).
This chapter contains sections titled: Errors Locating Most the Likely Angle Error Traverse Adjustments Applying a Rule of Construction: Reversing Course
Wistar rats had a single nare occluded on postnatal day 30, depriving the ipsilateral olfactory bulb of odor stimulation. The deprivation lasted for either 1–2 months (short-term) or 12 months (long-term). As previously reported, deprivation greatly reduced tyrosine hydroxylase immunoreactivity (the rate limiting enzyme for dopamine synthesis) in the glomerular layer of the ipsilateral olfactory bulb. The nare was then reopened and odor response patterns of mitral/tufted cells were examined. The proportion of mitral/tufted cell single-units responding to a single odor was enhanced by deprivation. Furthermore, the proportion of mitral/tufted cells responding to more than one odor was increased by deprivation, suggesting a decrease in discrimination. Finally, in undeprived bulbs, the dopamine D2 receptor antagonist spiperone mimicked the effects of deprivation on mitral/tufted cell odor response patterns. The results are interpreted as an activity- dependent dopamine modulation of lateral and feedback inhibition in the olfactory bulb, and are compared with similar events in the dark- adapted retina.
This chapter contains sections titled: Introduction Pretrial Discovery Initial Court Appearance Duties of a Surveyor in Court Conduct on the Stand Object of Litigation Surveyor–Attorney Relationship Court Trials Pretrials Types of Court Trials Oath, Questions, and Answers Direct Examination and Cross-examination Direct and Leading Questions Hearsay The Jury Witnesses Lay Witness Expert Witness Appointment of Expert Witnesses Duties of Expert Witnesses Opinion Evidence Hypothetical Questions Cause and Effect Textbooks and Treatises Use of Photographs Power to Compel Expert to Testify Cross-Examination of Expert Witness Expert Witness Fees Amount of Expert Witness Fee Is Subject to Cross-Examination Discovery by Interrogatories, Depositions, Admissions, or Production of Documents Survey Must Be Done by Surveyor Preparation for Testimony View of Site by the Court
Written by a neurobiologist and a psychologist, this volume presents a new theory of olfactory perception. Drawing on research in neuroscience, physiology, and ethology, Donald A. Wilson and Richard J. Stevenson address the fundamental question of how we navigate through a world of chemical encounters and provide a compelling alternative to the reception-centric view of olfaction. The major research challenge in olfaction is determining how the brain discriminates one smell from another. Here, the authors hold that olfaction is generally not a simple physiochemical process, but rather a plastic process that is strongly tied to memory. They find the traditional approach-which involves identifying how particular features of a chemical stimulus are represented in the olfactory system-to be at odds with historical data and with a growing body of neurobiological and psychological evidence that places primary emphasis on synthetic processing and experiential factors. Wilson and Stevenson propose that experience and cortical plasticity not only are important for traditional associative olfactory memory but also play a critical, defining role in odor perception and that current views are insufficient to account for current and past data. The book includes a broad comparative overview of the structure and function of olfactory systems, an exploration into the mechanisms of odor detection and olfactory perception, and a discussion of the implications of the authors' theory. Learning to Smell will serve as an important reference for workers within the field of chemical senses and those interested in sensory processing and perception.
Olfactory information is synthesized within the olfactory cortex to provide not only an odor percept, but also a contextual significance that supports appropriate behavioral response to specific odor cues. The piriform cortex serves as a communication hub within this circuit by sharing reciprocal connectivity with higher processing regions, such as the lateral entorhinal cortex and amygdala. The functional significance of these descending inputs on piriform cortical processing of odorants is currently not well understood. We have employed optogenetic methods to selectively stimulate lateral and basolateral amygdala (BLA) afferent fibers innervating the posterior piriform cortex (pPCX) to quantify BLA modulation of pPCX odor-evoked activity. Single unit odor-evoked activity of anaesthetized BLA-infected animals was significantly modulated compared with control animal recordings, with individual cells displaying either enhancement or suppression of odor-driven spiking. In addition, BLA activation induced a decorrelation of odor-evoked pPCX ensemble activity relative to odor alone. Together these results indicate a modulatory role in pPCX odor processing for the BLA complex, which could contribute to learned changes in PCX activity following associative conditioning.
ABSTRACT Current methods can, in a non-invasive manner, assess neural activity in all areas of the human brain but the olfactory bulb (OB). The OB is intimately involved in a long list of olfactory tasks, has been suggested to fulfill a role comparable to that of V1 and the thalamus in the visual system, and have been closely linked to a wide range of neuropathologies. Here we present a method for non-invasive recording of signals from the human OB with millisecond precision. We demonstrate that signals obtained via recordings from EEG electrodes at the nasal bridge represent responses from the olfactory bulb - recordings we term Electrobulbogram (EBG). The EBG is localized to the OB, is reliable, and follows response patterns demonstrated in non-human animal models. The EBG will aid future olfactory-related translational work but can also easily be implemented as an everyday clinical tool to detect pathology-related changes in human central olfactory processing in neurodegenerative diseases.
Perceptual learning is an enhancement in discriminability of similar stimuli following experience with those stimuli. Here, we examined the efficacy of adding additional active training following a standard training session, compared with additional stimulus exposure in the absence of associated task performance. Mice were trained daily in an odor-discrimination task, and then, several hours later each day, received 1 of 3 different manipulations: 1) a second active-training session, 2) non-task-related odor exposure in the home cage, or 3) no second session. For home-cage exposure, odorants were presented in small tubes that mice could sniff and investigate for a similar period of time as in the active discrimination task each day. The results demonstrate that daily home-cage exposure was equivalent to active odor training in supporting improved odor discrimination. Daily home-cage exposure to odorants that did not match those used in the active task did not improve learning, yielding outcomes similar to those obtained with no second session. Piriform cortical local field potential recordings revealed that both sampling in the active learning task and investigation in the home cage evoked similar beta band oscillatory activity. Together the results suggest that odor-discrimination learning can be significantly enhanced by addition of odor exposure outside of the active training task, potentially because of the robust activity evoked in the olfactory system by both exposure paradigms. They further suggest that odorant exposure alone could enhance or maintain odor-discrimination abilities in conditions associated with olfactory impairment, such as aging or dementia.
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